ECO A42
6 named openings and variations are classified as A42. ECO (Encyclopaedia of Chess Openings) codes group openings from A00 to E99 by their opening moves.
- Modern Defense: Averbakh SystemA421. d4 g6 2. c4 Bg7 3. Nc3 d6 4. e4
- Modern Defense: Averbakh Variation, Pseudo-SämischA421. d4 g6 2. c4 Bg7 3. e4 d6 4. Be3 Nf6 5. f3
- Modern Defense: Kotov VariationA421. d4 g6 2. c4 Bg7 3. Nc3 d6 4. e4 Nc6
- Modern Defense: Randspringer VariationA421. d4 g6 2. c4 Bg7 3. Nc3 d6 4. e4 f5
- Pterodactyl DefenseA421. Nf3 c5 2. c4 g6 3. d4 Bg7 4. e4 Qa5+ 5. Nc3 d6
- Pterodactyl Defense: Central, BogoluboviaA421. d4 g6 2. c4 Bg7 3. e4 d6 4. Nc3 c5 5. Nge2 Qa5